[php] How to check if a row exists in MySQL? (i.e. check if an email exists in MySQL)

I need help checking if a row exists in the database. In my case, that row contains an email address. I am getting the result:

email no longer exists [email protected]

This is the code I'm currently using:

if (count($_POST)) {
    $email = $dbl->real_escape_string(trim(strip_tags($_POST['email'])));

    $query = "SELECT `email` FROM `tblUser` WHERE `email` = '$email'";
    $result = mysqli_query($dbl, $query);
    if (is_resource($result) && mysqli_num_rows($result) == 1) {
        $row = mysqli_fetch_assoc($result);
        echo $email . " email exists " .  $row["email"] . "\n";
    } else {
        echo "email no longer exists" . $email . "\n";

Is there a better way to check if a row exists in MySQL (in my case, check if an email exists in MySQL)?

This question is related to php mysql mysqli pdo

The answer is

The following are tried, tested and proven methods to check if a row exists.

(Some of which I use myself, or have used in the past).

Edit: I made an previous error in my syntax where I used mysqli_query() twice. Please consult the revision(s).


if (!mysqli_query($con,$query)) which should have simply read as if (!$query).

  • I apologize for overlooking that mistake.

Side note: Both '".$var."' and '$var' do the same thing. You can use either one, both are valid syntax.

Here are the two edited queries:

$query = mysqli_query($con, "SELECT * FROM emails WHERE email='".$email."'");

    if (!$query)
        die('Error: ' . mysqli_error($con));

if(mysqli_num_rows($query) > 0){

    echo "email already exists";


    // do something


and in your case:

$query = mysqli_query($dbl, "SELECT * FROM `tblUser` WHERE email='".$email."'");

    if (!$query)
        die('Error: ' . mysqli_error($dbl));

if(mysqli_num_rows($query) > 0){

    echo "email already exists";


    // do something


You can also use mysqli_ with a prepared statement method:

$query = "SELECT `email` FROM `tblUser` WHERE email=?";

if ($stmt = $dbl->prepare($query)){

        $stmt->bind_param("s", $email);


            $email_check= "";         

            if ($stmt->num_rows == 1){

            echo "That Email already exists.";


Or a PDO method with a prepared statement:

$email = $_POST['email'];

$mysql_hostname = 'xxx';
$mysql_username = 'xxx';
$mysql_password = 'xxx';
$mysql_dbname = 'xxx';

try {
$conn= new PDO("mysql:host=$mysql_hostname;dbname=$mysql_dbname", $mysql_username, $mysql_password); 
     $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
     exit( $e->getMessage() );

// assuming a named submit button

        try {
            $stmt = $conn->prepare('SELECT `email` FROM `tblUser` WHERE email = ?');
            $stmt->bindParam(1, $_POST['email']); 
            while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {

        catch(PDOException $e) {
            echo 'ERROR: ' . $e->getMessage();

    if($stmt->rowCount() > 0){
        echo "The record exists!";
    } else {
        echo "The record is non-existant.";

  • Prepared statements are best to be used to help protect against an SQL injection.


When dealing with forms and POST arrays as used/outlined above, make sure that the POST arrays contain values, that a POST method is used for the form and matching named attributes for the inputs.

  • FYI: Forms default to a GET method if not explicity instructed.

Note: <input type = "text" name = "var"> - $_POST['var'] match. $_POST['Var'] no match.

  • POST arrays are case-sensitive.


Error checking references:

Please note that MySQL APIs do not intermix, in case you may be visiting this Q&A and you're using mysql_ to connect with (and querying with).

  • You must use the same one from connecting to querying.

Consult the following about this:

If you are using the mysql_ API and have no choice to work with it, then consult the following Q&A on Stack:

The mysql_* functions are deprecated and will be removed from future PHP releases.

  • It's time to step into the 21st century.

You can also add a UNIQUE constraint to (a) row(s).


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